Genus 92. 



GRASS FAMILY. 



2 59 



19. Poa compressa L. Wire-grass. Flat-stemmed 

 Meadow-grass. English Blue-grass. Fig. 622. 



Poa compressa L. Sp. PI. 69. 1753. 



Pale bluish green, glabrous, culms 6-2 tall, decumbent 

 at the base, from long horizontal rootstocks, smooth, much 

 flattened. Sheaths loose, flattened, shorter than the inter- 

 nodes; ligule i" long; blades i'-4' long, about 1" wide, 

 smooth beneath, rough above; panicle usually contracted, 

 the branches erect or ascending, 1' long or less, spikelet- 

 bearing nearly to the base; spikelets 3-9-flowered, 1V-3" 

 long; lower scales acute, 3-nerved; flowering scales i"-ii" 

 long, obscurely 3-nerved, the nerves sparingly pubescent 

 toward the base. 



Waste places and cultivated grounds and woods almost 

 throughout North America. Ascends to 2100 ft. in Virginia. 

 Naturalized from Europe. Native also of Asia. Varies from 

 weak and slender to quite stiff. Squitch-grass. June-Aug. 



20. Poa arachnifera Torr. Texas Blue-grass. Fig. 623. 



Poa arachnifera Torr. Marcy's Exped. 301. 1853. 



Culms tufted, i°-3° tall, smosth and glabrous, from 

 running rootstocks ; sterile shoots from one-half as 

 long as the culms to equalling them. Sheaths longer 

 than the internodes, smooth or roughish, hyaline on the 

 margins; ligule a short membranous ring; blades 

 linear, erect, usually folded when dry, smooth beneath, 

 rough above, i4'-9' long, iV's" broad, abruptly acute ; 

 panicle dense and contracted, sometimes interrupted 

 below, z'-6¥ long, 4'-ii' broad, its branches ascend- 

 ing or erect; spikelets numerous, 4-7-flowered, the 

 scales acuminate, the empty ones hispidulous on the 

 midnerve; flowering scales 2"-2j" long, often pointed, 

 pubescent at the base with copious long cobwebby 

 hairs, 5-nerved, the midnerve and lateral nerves pilose 

 below the middle. 



Prairies, Kansas to New Mexico, south to Louisiana 

 and Texas. Also introduced in Florida. April-May. 



21. Poa eminens Presl. Large-flowered Spear- 

 grass. Fig. 624. 



P. eminens Presl, Rel. Haenk. 1 : 273. 1830. 



P. glumaris Trin. Mem. Acad. St. Petersb. (VI.) 1 : 379. 



1831. 



Smooth and glabrous, culms 6'-3° tall, erect or as- 

 surgent, simple. Sheaths loose, usually shorter than the 

 internodes ; ligule i" long, truncate ; blades 4'-io' long, 

 i"-4" wide; panicle 4'-io' in length, the branches erect 

 or ascending, i'-2' long; spikelets 3-5-flowered, 4"-6" 

 long; lower scales about equal, acute, slightly scabrous 

 on the keel, the first 1-3-nerved, the second 3-nerved, 

 rarely 5-nerved; flowering scales 3"-4" long, usually 

 acutish, scabrous, 5-7-nerved, pubescent at base and on 

 the lower part of the midnerve and lateral nerves, not 

 webbed. 



Beaches and shores, Labrador to Quebec, Washington and 

 Alaska. Summer. 



